1. The number of independent loops for a network with a n nodes and b branches is
(a) n -1 (b) b - n
(c) b œ n + 1
(d) independent of the number of nodes
2. A lossless transmission line having 50 characteristic impedance and length 4 short circuited at one end and connected to an ideal voltage source of 1V at the other end. The current drawn from the voltage source is
(a) 0 (b) 0.02 A
(c) 8 (d) None of the above
3. The p-type substrate in a conventional pn-junction isolated integrated circuit should be connected to
(a) nowhere, i.e. left floating
(b) a dc ground potential
(c) the most positive potential available in the circuit
(d) the most negative potential available in the circuit
4. If a transistor is operating with both of its junctions forward biased, but with the collector base forward bias greater than the emitter œ base forward bias, then it is operating in the
(a) forward active mode (b) reverse saturation mode
(c) reverse active mode (d) forward saturation mode
5. The common-emitter short-circuit current gain ß of a transistor
(a) is a monotonically increasing function of the collector current IC
(b) is a monotonically decreasing function of IC
(c) increases with IC, for low IC , reaches maximum and then decreases with
further increase in IC
(d) is not a function of IC
6. A n-channel silicon ( E) 1.1 eV
= MOSFET was fabricated using n+ poly-silicon gate g
and the threshold voltage was found to be 1V. Now, if the gate is changed to p+ poly-silicon, other things remaining the same, the new threshold voltage should
be
(a) -0.1 V (b) 0 V (c) 1.0 V (d) 2.1 V
7. Schottky clamping is resorted in TTL gates
(a) to reduce propagation delay (b) to increase noise margins
(c) to increase packing density (d) to increase fan-out
8. A pulse train can be delayed by a finite number of clock periods using
(a) a serial-in serial-out shift register
(b) a serial-in parallel-out shift register
(c) a parallel-in serial-out shift register
(d) a parallel-in parallel-out shift register
9. A 12-bit ADC is operating with a 1 sec clock period and the total conversion time is seen to be 14 secs. The ADC must be of the
(a) flash type (b) counting type
(c) integrating type
(d) successive approximation type
10. The total number of memory accesses involved (inclusive of the op-code fetch)
when an 8085 processor executes the instruction LDA 2003 is
(a) 1 (b) 2 (c) 3 (d) 4
11. The trigonometric Fourier series of an even function of time does not have the
(a) dc term (b) cosine terms
(c) sine terms (d) odd harmonic terms
12. The Fourier transform of a real valued time signal has
(a) odd symmetry (b) even symmetry
(c) conjugate symmetry (d) no symmetry
13. A rectangular pulse of duration T is applied to a filter matched to this input. The
output of the filter is a
(a) rectangular pulse of duration T (b) rectangular pulse of duration 2T
(c) triangular pulse (d) sine function
14. The image channel rejection in a superheterodyne receiver comes from
(a) IF stages only (b) RF stages only
(c) detector and RF stages only (d) detector RF, and IF stages
15. The capacitance per unit length and the characteristic impedance of a lossless
Z respectively. The velocity of a traveling wave on
transmission line are C and o
the transmission line is
(a)ZC (b) 1 (c) o (d)z/c
o
16. A transverse electromagnetic wave with circular polarization is received by a
dipole antenna. Due to polarization mismatch, the power transfer efficiency from
the wave to the antenna is reduced to about
(a) 50% (b) 35.3% (c) 25% (d) 0%
17. A metal sphere with 1m radius and a surface charge density of 10 Coulombs/m2 is enclosed in a cube of 10m side. The total outward electric displacement normal to the surface of the cube is
(a) 40p Coulombs (b) 10p Coulombs
(c) 5p Coulombs (d) None of the above
18. A uniform plane wave in air is normally incident on infinitely thick slab. If the refractive index of the glass slab is 1.5, then the percentage of incident power
that is reflected from the air-glass interface is
(a) 0% (b) 4% (c) 20% (d) 100%
19. In a bipolar transistor at room temperature, if the emitter current is doubled the voltage across its base-emitter junction
(a) doubles (b) halves
(c) increases by about 20 mV (d) decreases by about 20 mV
20. As npn transistor has a beta cutoff frequency fß of 1 MHz, and common emitter f and short circuit low-frequency current gain ß of 200. It unity gain frequency T the alpha cutoff frequency fa respectively are
(a) 200 MHz, 201 MHz (b) 200 MHz, 199 MHz
(c) 199 MHz, 200 MHz (d) 201 MHz, 200 MHz
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